Where you get ingasuras fossil in fossil fighters

After you beat the game, beat Saurhead at the Fossil Stadium Locker Room. He will challenge you to 3 battles (All rank 12 Vivosaurs). Saurhead#1: Brontoth, M-Raptor and Coelo (He uses Vivosaurs that have really high Support Effects). Saurhead#2: Perso, Salto and Apato (He used them for high LP and Defense to give you a hard time. So don't let Apato use Sacrifice). Saurhead#3: T-Rex, Gorgo and Guan (Guan Boosts T-Rex's attack by 90% so you might wanna him an Accuracy disadvantage or a mega Defense raise) .